Analysis of unsteady solid-propellant combustion models (review)

Recent studies of solid-propellant combustion models are briefly analyzed. The models are divided into purely one-dimensional (classical and phenomenological models with various generalizations of the Zel’dovich approach) and non-one-dimensional. The latter include models with local non-one-dimensionality, which is always accompanied by local unsteadiness. This all can be eliminated by averaging. The main disadvantage of unsteady solid-propellant combustion models, which is no fault of their authors, is the same as in the case of steady-state models: the lack of detailed information on chemical and physical processes in the condensed phase. Impropriety of extending the purely one-dimensional approach to the instability region is noted. Possible directions for further development of unsteady (and quasi-steady-state) solid-propellant combustion models for homogeneous compositions may involve accounting for local non-one-dimensionality and the unsteadiness due to instability of the subsurface reactions zone and verification of the possibility of the existence of chemical instability capable of causing similar non-one-dimensionality and unsteadiness.